1. Field of the Invention
This invention relates to gas compressors, and is directed more particularly to a relatively inexpensive high pressure gas compressor suitable for charging the tanks of vehicles operating on compressed natural gas.
2. Description of the Prior Art
Compressors currently used in compressed natural gas (CNG) fueling stations for vehicles typically provide three or four stages of compression. The cost of such compressors is high because a separate compressor cylinder and piston unit is used for each compression stage.
Because the CNG compressors now in use for fueling stations are designed for relatively quick delivery, and because in order to obtain quick delivery, the compressor must discharge relatively large quantities of gas at high pressures, the compressors are necessarily large and expensive.
Relatively simple and inexpensive units are suitable for residential or small fleet use, even though requiring a relatively long time for a vehicle tank filling. The fact that such compressors for residential use, and the like, have design features similar to those of large capacity compressors, for "fast fill" operations, the cost per unit delivery capacity of the compressor systems renders the currently used systems beyond the economic reach of residential CNG users.
Accordingly, there is a need for a high pressure natural gas compressor which is relatively inexpensive and suitable for residential or small fleet use in filling the tanks of CNG fueled vehicles.